import sys

# str1 = sys.stdin.readline()
# print(str1)
#
# num1 = input("请输入一个数字")
# print(num1)
#
# sys.stdout.write("hello")
# print(" world")

# file = open("a.txt", 'r', buffering=1, encoding='utf-8')
# print(file.read())
# file.close()

# with open("a.txt", 'r', buffering=1, encoding='utf-8') as file2:
    # print(file2.readline())
    # print(file2.readline())
    # print(file2.readlines())

with open("a.txt", 'a', encoding='utf-8', buffering=1) as file3:
    file3.write("\nhello world")